Difference between revisions of "Denavit-Hartenberg parameters"

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[[File:dh-params-general.png|right|250px]]
 
[[File:dh-params-general.png|right|250px]]
When the [[Assigning coordinate frames|coordinate frames]] are assigned to a manipulator, the transformation between each two consecutive frames has to be described. Therefor the 4 Denavit-Hartenberg parameters <math>\theta</math>, <math>d</math>, <math>l</math> and <math>\alpha</math> are used. The figure on the right shows two coordinate frames <math>K_{n-1}</math> and <math>K_n</math> and illustrates the parameters. The corresponding [[Common normal|common normal]] is represented by a dashed red line. The Denavit-Hartenberg parameters are defined as follows:
+
When the [[Assigning coordinate frames|coordinate frames]] are assigned to a manipulator, the transformation between each two consecutive frames has to be described. Therefor the 4 Denavit-Hartenberg parameters <math>\theta</math>, <math>d</math>, <math>l</math> and <math>\alpha</math> are used. The figure on the right shows two coordinate frames <math>K_{n-1}</math> and <math>K_n</math> and the corresponding [[Common normal|common normal]] represented by a dashed red line. The figure illustrates the Denavit-Hartenberg parameters, that are defined as follows:
  
 
;<math>\theta</math>
 
;<math>\theta</math>

Revision as of 18:19, 12 November 2015

← Back: Assigning coordinate frames Overview: Denavit-Hartenberg Convention Next: A-matrices
Dh-params-general.png

When the coordinate frames are assigned to a manipulator, the transformation between each two consecutive frames has to be described. Therefor the 4 Denavit-Hartenberg parameters \theta, d, l and \alpha are used. The figure on the right shows two coordinate frames K_{n-1} and K_n and the corresponding common normal represented by a dashed red line. The figure illustrates the Denavit-Hartenberg parameters, that are defined as follows:

\theta
The angle \theta is defined as the angle about the z_{n-1}-axis to align x_{n-1} with the new x_{n}-axis.
d
d is the offset or translation, respectively, along the z_{n-1}-axis from the origin of K_{n-1} to the intersection with the common normal.
l
The parameter l corresponds to the length of the common normal which is equivalent to the translation along it.
If the related joint J_n is a revolute joint, l can also be regarded as the radius of the rotation about the z_{n-1}-axis
\alpha
The angle \alpha corresponds to the angle about the common normal to align the z_{n-1}-axis with the new z_{n}-axis
Dh-params-steps.png